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CHANDRAO: Help

CHANDRAO - Chandra Proposals


Overview

This database contains all of the accepted targets to be observed by the Chandra X-Ray Observatory (CXO, formerly known as the Advanced X-ray Astrophysics Facility or AXAF) as part of the Performance Verification and Calibration (PVC) phase and also contains all of the Cycle 1 and Cycle 2 Guaranteed Time Observers (GTO) and General Observer (GO) targets, and Director's Discretionary Time (DDT) targets that have already been observed.

The PVC phase was during the first few months of the CXO mission; some of the calibration observations that are for monitoring purposes will be performed in later mission cycles. All calibration data (entries with Type = CAL in this database) are placed immediately into the CXO public data archive at the Chandra X-Ray Observatory Center (CXC); please see the Web page at http://asc.harvard.edu/ for more information on the CXC data archive). GTO observations during Cycle 1 or 2 will occupy 100% of months 3-4, 30% of months 5-22, and 15% of the available time for the remainder of the mission. Guaranteed Time Observers will have the same proprietary data rights as General Observers (i.e., their data will be placed in the public CXC archive 12 months after they have received the data in usable form). More information on these targets and observations is available at the CXC web site at http://asc.harvard.edu/.

This HEASARC database is recreated on a weekly basis by querying the CXC Target Search Form webpage at http://asc.harvard.edu/targets/


References

The original version of this target list was provided as part of the NASA Research Announcement for the Chandra (AXAF) Cycle 1 General Observer (GO) Program (NRA 97-OSS-14). The current version of the database is recreated on a weekly basis by querying the CXC Target Search Form webpage at http://asc.harvard.edu/targets/

Provenance

This database table is updated by the HEASARC on a weekly basis by querying the CXC Target Search Form webpage at http://asc.harvard.edu/targets/

Parameters

Sequence_Number
The sequence number to which the observation corresponds (assigned by CXC).

Prop_Number
The proposal number to which the target corresponds (assigned by CXC).

Obs_ID
A unique Chandra observation identifier (assigned by CXC).

Cycle
The cycle number in which the proposal to observe the particular target was submitted. Note that any observations which the CXC have not assigned proposal numbers have been defaulted to a value of 0 for this parameter in this HEASARC database.

Type
There are five general types of target: those accepted in a General Observer (GO) proposal (type = 'GO'), those accepted in a Guaranteed Time Observing (GTO) proposal (type ='GTO'), those used for a Calibration observation (type = 'CAL'), those accepted as Targets of Opportunity (type = 'TOO'), and those observed as Director's Discretionary Time (type = 'DDT'). Please note that some DDT targets may have been designated as TOO targets.

PI
The last name of the Principal Investigator. Notice that this is not always an unambiguous identifier, since there are a number of last names (e.g., Drake and White) which are shared by more than one astronomer. If in doubt, it is recommended that that the CXC website be consulted, e.g., http://cxc.harvard.edu/target_lists/cycle1/abstracts_cyc1.html lists the full PI name for all accepted Cycle 1 programs.

Name
The source designation or target name as provided by the Principal Investigator (PI).

RA
The right ascension in the specified equinox. The CXC table from which this database was created listed positions in J2000 coordinates, with the RA listed to the nearest 0.01 seconds of time. Objects with no specific positional information available, such as TOOs for particular classes of phenomena such as GRBs and black hole transients have been assigned 0 RA and Declination in the default equinox (2000 for the Web-based Browse system, 1950 for the captive account BROWSE system).

Dec
The declination in the specified equinox. The CXC table from which this database was created listed positions in J2000 coordinates, with declination listed to the nearest 0.01 arcsecond. Objects with no specific positional information available, such as TOOs for particular classes of phenomena such as GRBs and black hole transients have been assigned 0 RA and Declination in the default equinox (2000 for the Web-based Browse system, 1950 for the captive account BROWSE system).

LII
The galactic longitude. Objects with no specific positional information available, such as TOOs for particular classes of phenomena such as GRBs and black hole transients have been assigned 0 LII and BII.

BII
The galactic latitude. Objects with no specific positional information available, such as TOOs for particular classes of phenomena such as GRBs and black hole transients have been assigned 0 LII and BII.

Detector
The detector requested for the exposure. There are 2 focal-plane scientific instruments, the AXAF CCD Imaging Spectrometer (ACIS) and the High Resolution Camera (HRC). The ACIS has 2 arrays of CCDs: the ACIS imaging array (ACIS-I) is optimized for imaging wide fields, while the ACIS spectroscopic array (ACIS-S) is optimized for grating spectroscopy and for imaging smaller fields. The HRC consists of 2 microchannel plate array which are used as the primary detection devices: the HRC-I is optimized for direct imaging, while the HRC-S is optimized for imaging the dispersed flux from the Low Energy Transmission Grating (LETG). Thus, there are 4 possible detectors: ACIS-I, ACIS-S, HRC-I, and HRC-S.

Grating
The grating requested for the exposure. There are 2 objective transmission gratings: the High Energy Transmission Grating (HETG) and the Low Energy Transmission Grating (LETG). The ACIS-S detector will normally be used to read out the HETG spectra, while then HRC-S detector will normally be used to read out the LETG spectra. Thus, there are 3 possible grating selections: LETG, HETG, and NONE (i.e., no grating requested).

Exposure
The approved exposure time in kiloseconds (ksec). The actual exposure time may be somewhat different than the approved exposure time, in general.

Date_Observed
The date on which the observation was made, if available.

Status
The status of the observation. Possible values are Unobserved, Scheduled, Partially Observed, Observed or Archived.


Contact Person

Questions regarding the CHANDRAO database table can be addressed to the HEASARC User Hotline.
If you have any problems, please consult the help page or mail ledas-help@star.le.ac.uk
 
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